1. Field of the Invention
The present invention relates to a controller for an actuator which moves or vibrates an object.
2. Description of the Prior Art
Actuators for operating an object in a predetermined manner are known. For instance, a material testing machine as disclosed in Japanese Patent Laid-open No. Hei 4-301738 is a device for testing the strength of a specimen by giving predetermined vibrations thereto using an actuator. In particular, feedback control is applied in this device to maintain a consistent excitation condition. This means enables vibrating a specimen under a desired condition. Further, data on a gain for feedback control (a feedback gain) is stored for every specimen in a database, so that a feedback gain to be applied for actual excitation is calculated based the data stored. To be specific, when vibration tests are carried out to various specimens having different dynamical characteristics, such as a mass, spring characteristics, attenuation characteristics, an excitation condition for a specimen whose dynamical characteristics are identical or similar to that of the object to be tested is read from the database and referred to in determination of a feed back gain for the test. An optimal feedback gain can be determined more easily in this manner than in a case where a base value for the calculation of an optimal gain is unknown.
The above devise, however, requires a database prepared in advance. Further, data on base values is not yet available at the stage of preparation. Because of this, it takes time and trouble to determine an optimal gain value. Things are more troublesome in the case of a specimen whose characteristic data is not found in a data base. Worse, excitation conditions may be all met while calculations of an optimal value are repeatedly attempted while changing calculation conditions.